C#知识点(域名解析、正则式匹配)

using System.Net;

public static string domain2ip(string str)
{
string _return = "";
try
{
IPHostEntry hostinfo = Dns.GetHostByName(str);
IPAddress[] aryIP = hostinfo.AddressList;
_return = aryIP[0].ToString();

}
catch (Exception e)
{
_return = e.Message;
}
return _return;
}

using System.Text.RegularExpressions;

Match m = Regex.Match(ip, "(//d{1,3}//.){3}//d{1,3}");

if (m.Success)
data_ip = ip;//IP合法
else
{   //IP不合法
lab_prompt.Text = "服务器连接失败...";
this.btn_login.Enabled = false;
}